Microfeature workpieces (e.g., round wafers) are typically provided to microfeature device manufacturers with beveled edges. A variety of techniques are used to bevel the edges, including applying plasma jets to the workpiece, running a polishing tape along the edges, and contacting the edges with a conical abrasive surface. During the course of processing, layers of materials are built up on the microfeature workpiece and then planarized using mechanical and chemical-mechanical planarization and polishing processes (collectively “CMP”). As a result of these processes, the initially beveled edges of the microfeature workpiece also receive deposits, which can reduce or eliminate the beveled shape of these edges. During subsequent planarization operations, these edges can be a source for defects. In particular, the deposited layers at and near the edge of the workpiece may tend to peel or delaminate, causing defects in the edge region of the microfeature workpiece. Defects in the edge region can migrate to other portions of the microfeature workpiece during subsequent processing steps, so that the defects are not necessarily limited to only the peripheral region of the workpiece. Furthermore, particles released from the edge region can cause scratch defects at the parts of the workpiece as the particles are dragged across the workpiece surface during processing.
One proposed solution to the foregoing problem is to use the same beveling tools that initially bevel the edges of the workpiece to also bevel the workpiece at selected points during microfeature device fabrication. FIG. 1A illustrates a tool 10 configured for such a purpose. The tool 10 can include a plurality of processing stations 12 (e.g., beveling stations) housed in an enclosure 11. Input/output stations 13 are used to transfer microfeature workpieces into and out of the enclosure 11. A control and display panel 14 is used to control the motion of the workpieces within the enclosure 11 and the processes taking place at the processing stations 12.
FIG. 1B illustrates components of one such processing station 12. The components can include a wafer carrier 60 carrying a wafer 50 having two edges 54. A shaft 42 carries a conical support 40 having a conical, concave surface. An abrasive liner 20 is attached to the conical support 40 and both the conical support 40 and the wafer carrier 60 are rotated, as indicated by arrows R. The wafer 50 is then brought into contact with the spinning abrasive liner 20 to bevel one edge 54. Optionally, the remaining edge 54 can also be beveled after the wafer 50 is inverted on the carrier 60.
One drawback with the foregoing approach is that the tool 10, while effective for beveling workpiece edges, can be expensive. In particular, the tool can be expensive to acquire and, because it occupies a relatively large amount of clean-room floor space, can be expensive to own and maintain. Furthermore, the risk of damage to microfeature workpieces as they are shuttled back and forth between an edge bevel tool 10 and a CMP tool can further increase the overall cost of using such a tool.